1*2c2f96dcSApple OSS Distributions<h2>semaphore_create</h2> 2*2c2f96dcSApple OSS Distributions<hr> 3*2c2f96dcSApple OSS Distributions<p> 4*2c2f96dcSApple OSS Distributions<strong>Function</strong> - Create a new semaphore. 5*2c2f96dcSApple OSS Distributions<h3>SYNOPSIS</h3> 6*2c2f96dcSApple OSS Distributions<pre> 7*2c2f96dcSApple OSS Distributions<strong>kern_return_t semaphore_create</strong> 8*2c2f96dcSApple OSS Distributions <strong>(task_t</strong> <var>task</var>, 9*2c2f96dcSApple OSS Distributions <strong>semaphore_t</strong> <var>*semaphore</var>, 10*2c2f96dcSApple OSS Distributions <strong>int</strong> <var>policy</var>, 11*2c2f96dcSApple OSS Distributions <strong>int</strong> <var>value</var><strong>);</strong> 12*2c2f96dcSApple OSS Distributions</pre> 13*2c2f96dcSApple OSS Distributions<h3>PARAMETERS</h3> 14*2c2f96dcSApple OSS Distributions<dl> 15*2c2f96dcSApple OSS Distributions<dt> <var>task</var> 16*2c2f96dcSApple OSS Distributions<dd> 17*2c2f96dcSApple OSS Distributions[in task port] The task receiving the send right of the newly created semaphore. 18*2c2f96dcSApple OSS Distributions<p> 19*2c2f96dcSApple OSS Distributions<dt> <var>semaphore</var> 20*2c2f96dcSApple OSS Distributions<dd> 21*2c2f96dcSApple OSS Distributions[out send right] The port naming the created semaphore. 22*2c2f96dcSApple OSS Distributions<p> 23*2c2f96dcSApple OSS Distributions<dt> <var>policy</var> 24*2c2f96dcSApple OSS Distributions<dd> 25*2c2f96dcSApple OSS Distributions[in scalar] The blocked thread wakeup policy for the newly created semaphore. Valid policies are: 26*2c2f96dcSApple OSS Distributions<dl> 27*2c2f96dcSApple OSS Distributions<p> 28*2c2f96dcSApple OSS Distributions <dt> SYNC_POLICY_FIFO 29*2c2f96dcSApple OSS Distributions<dd> 30*2c2f96dcSApple OSS Distributionsa first-in-first-out policy for scheduling thread wakeup. 31*2c2f96dcSApple OSS Distributions <p> 32*2c2f96dcSApple OSS Distributions <dt> SYNC_POLICY_FIXED_PRIORITY 33*2c2f96dcSApple OSS Distributions<dd> 34*2c2f96dcSApple OSS Distributionsa fixed priority policy for scheduling thread wakeup. 35*2c2f96dcSApple OSS Distributions </dl> 36*2c2f96dcSApple OSS Distributions <p> 37*2c2f96dcSApple OSS Distributions<dt> <var>value</var> 38*2c2f96dcSApple OSS Distributions<dd> 39*2c2f96dcSApple OSS Distributions[in scalar] The initial value of the semaphore count. 40*2c2f96dcSApple OSS Distributions</dl> 41*2c2f96dcSApple OSS Distributions<h3>DESCRIPTION</h3> 42*2c2f96dcSApple OSS Distributions<p> 43*2c2f96dcSApple OSS DistributionsThe <strong>semaphore_create</strong> function creates a new semaphore, associates the 44*2c2f96dcSApple OSS Distributionscreated semaphore with the specified task, and returns a send right 45*2c2f96dcSApple OSS Distributionsnaming the new semaphore. In order to support a robust 46*2c2f96dcSApple OSS Distributionsproducer/consumer communication service, Interrupt Service Routines 47*2c2f96dcSApple OSS Distributions(ISR) must be able to signal semaphores. The semaphore synchronizer 48*2c2f96dcSApple OSS Distributionsservice is designed to allow user-level device drivers to perform 49*2c2f96dcSApple OSS Distributionssignal operations, eliminating the need for event counters. Device 50*2c2f96dcSApple OSS Distributionsdrivers which utilize semaphores are responsible for creating (via 51*2c2f96dcSApple OSS Distributions<strong>semaphore_create</strong>) and exporting (via <strong>device_get_status</strong>) 52*2c2f96dcSApple OSS Distributionssemaphores for 53*2c2f96dcSApple OSS Distributionsuser level access. Device driver semaphore creation is done at device 54*2c2f96dcSApple OSS Distributionsinitialization time. Device drivers may support multiple semaphores. 55*2c2f96dcSApple OSS Distributions<h3>RETURN VALUES</h3> 56*2c2f96dcSApple OSS Distributions<dl> 57*2c2f96dcSApple OSS Distributions <p> 58*2c2f96dcSApple OSS Distributions<dt> <strong>KERN_INVALID_ARGUMENT</strong> 59*2c2f96dcSApple OSS Distributions<dd> 60*2c2f96dcSApple OSS DistributionsThe task argument or the policy argument was invalid, 61*2c2f96dcSApple OSS Distributions or the initial value of the semaphore was invalid. 62*2c2f96dcSApple OSS Distributions <p> 63*2c2f96dcSApple OSS Distributions<dt> <strong>KERN_RESOURCE_SHORTAGE</strong> 64*2c2f96dcSApple OSS Distributions<dd> 65*2c2f96dcSApple OSS DistributionsThe kernel could not allocate the semaphore. 66*2c2f96dcSApple OSS Distributions <p> 67*2c2f96dcSApple OSS Distributions<dt> <strong>KERN_SUCCESS</strong> 68*2c2f96dcSApple OSS Distributions<dd> 69*2c2f96dcSApple OSS DistributionsThe semaphore was successfully created. 70*2c2f96dcSApple OSS Distributions</dl> 71*2c2f96dcSApple OSS Distributions<h3>RELATED INFORMATION</h3> 72*2c2f96dcSApple OSS Distributions<p> 73*2c2f96dcSApple OSS DistributionsFunctions: 74*2c2f96dcSApple OSS Distributions<a href="semaphore_destroy.html"><strong>semaphore_destroy</strong></a>, 75*2c2f96dcSApple OSS Distributions<a href="semaphore_signal.html"><strong>semaphore_signal</strong></a>, 76*2c2f96dcSApple OSS Distributions<a href="semaphore_signal_all.html"><strong>semaphore_signal_all</strong></a>, 77*2c2f96dcSApple OSS Distributions<a href="semaphore_wait.html"><strong>semaphore_wait</strong></a>, 78*2c2f96dcSApple OSS Distributions<a href="device_get_status.html"><strong>device_get_status</strong></a>. 79